Color printing apparatus for potentiometric recording instruments

ABSTRACT

Writing apparatus in multicurve electronic potentiometric recording instruments to record the values of a plurality of variables on a continuous movement single chart. The writing apparatus comprises a movable writing carriage, means for inking in a plurality of colours and changeover means for selecting the variables. The writing carriage moves parallel to itself to assume the stamping and inking position and oscillates at right angles to the direction of movement to effect the stamping and inking operations.

United States Patent Inventor Ugo Carpino Milan, Italy Appl. No. 776,044 Filed Nov. 15, 1968 Patented May 4, 1971 Assignee Pio Guardigli Milan, Italy Priority Nov. 20, 1967 Italy 22899/67 COLOR PRINTING APPARATUS FOR POTENTIOMETRIC RECORDING INSTRUMENTS 6 Claims, 6 Drawing Figs.

US. Cl 346/46, 346/34 Int. Cl G0ld 9/34 Field of Search 346/34, 46, 141

[56] References Cited UNITED STATES PATENTS 1,358,896 11/1920 Thwing 346/140 2,191,673 2/1940 Moore 346/46 2,676,513 4/1954 Bowditch et al. 346/46 3,144,296 8/1964 Hohl 346/141 FOREIGN PATENTS 633,527 8/1936 Germany 346/117 Primary Examiner.loseph W. Hartary Attorney-Young and Thompson ABSTRACT: Writing apparatus in multicurve electronic potentiometric recording instruments to record the values of a plurality of variables on a continuous movement single chart. The writing apparatus comprises a movable writing carriage, means for inking in a plurality of colours and changeover means for selecting the variables. The writing carriage moves parallel to itself to assume the stamping and inking position and oscillates at right angles to the direction of movement to effect the stamping and inking operations.

BACKGROUND OF THE INVENTION It is known that potentiometric instruments serve essentially to measure small direct-current electromotive forces with considerable accuracy and that in the field of industrial measurements the use of automatic-balancing potentiometric instruments is today remarkably widespread, above all for making temperature measurements by means of thermocouples.

The general basic scheme of this type of instrument is also known: a voltage drop E existing between the end of the resistance and the slider of the potentiometer is compared with the electromotive force E to be measured. The potentiometer is fed from a source of electromotive force which is perfectly constant and of known value En, so that E is also known and depends solely on the position of the slider of the potentiometer. The difference between E and E is amplified by means of an amplifier and is used to control a reversible servomotor which actuates the reading pointer of the instrument and the slider of the potentiometer through a reduction gear. If the voltages E and E are equal, the system is in balance and the position adopted by the pointer of the instrument on the scale furnishes the measurement of the electromotive force E. If the voltage E is different to E the servomotor rotates forward or backward (according to whether E is greater than E or E is smaller than E until a new state of balance is found which corresponds to the new value of E. In recording instruments, instead of the servomotor actuating an ordinary reading pointer, it actuates a pen writing system which records the measured value on a suitable chart sheet movable as a function of time. i

The same principle of operation is used for constructing multicurve recorders, that is recorders adapted to record the values of a plurality of variables (generally six or 12 or 24) on a single chart. In this case, the instrument is equipped with a bipolar rotary changeover switch actuated by a small auxiliary motor and which connects the inputs of the measuring circuit successively and cyclically to the different variables to be measured. As a rule, the recording is effected in dots, that is a dot is imprinted on the .chart in correspondence with each variable measured and indentifies the value thereof. Ultimately, a representation of the course of the variables measured is obtained on the chart by means of dotted lines.

In order to be able to distinguish one variable from another,

the dots on the chart are stamped in different colors, one for each variable, or are marked or identified by means of different symbols.

SUMMARY OF THE INVENTION The present invention relates to a writing apparatus for potentiometn'c recorders adapted to permit dot recording of a plurality of variables by means of colored dots or symbols in which considerable improvements have been made in comparison with the systems of this kind heretofore employed and which consequently affords considerable advantages from the constructional aspect and from that of functionality.

The apparatus according to the invention essentially comprises, in a holding and supporting frame, a writing carriage, means for effecting the movements thereof, means for inking in a plurality of colors and changeover means for connecting in the recorder circuit one after another the variables of which it is desired to plot the curves and is characterized essentially by the fact that the writing carriage is moved parallel to itself by a mechanical lever drive to assume the stamping and inking positions and is made to oscillate at right angles to the direction of movement by a movable frame to effect the stamping and inking operations, respectively, said movable frame being controlled by a cam the shaft of which is in a fixed ratio of rotation to the shaft which moves the inking means to select the color thereof from time to time. I

The invention will now be described in greater detail with reference to a preferred constructional form thereof illustrated in the accompanying drawings so as to display other important characteristics and advantages of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIGS. 1, 2 and 3 are diagrammatic front and side views of the mechanism of the system according to the invention, while;

FIG. 3a shows a position of the control cam of the movable frame which is different from the position shown in FIG. 3;

FIG. 4 is a diagrammatic view on a larger scale of the writing carriage of the system of FIGS. 1 to 3, of which carriage;

FIG. 5 is a section of the line V- V of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The system of FIGS. I to 3 essentially comprises, mounted together on a suitable frame I, a writing carriage 2 adapted to slide forward and backward on a bar 3 disposed parallel to the x-axis of the graph to be plotted, a lever system 4, 5, 6 which controls the sliding of the carriage 2, a wheel 7 carrying the inking pads 8, a stamping frame 9, l0 and 11 and a stamping and changeover mechanism 12.

The writing carriage 2 is shown in detail in FIGS. 4 and 5. It is constituted by the hollow cylindrical core 13 terminating in two bushes I4 which permit the sliding of the carriage without any play on the'bar 3 of the mechanism. Pivoted on the outside of the core 13 are a fixed frame 15, a movable frame 16 and a double-toothed wheel 17. All the parts described are free to turn about the core 13 and are held in position laterally by means of suitable resilient spacing washers. e

The fixed frame 15 carries a pin 18 by means of which it is connected to the lever 4 (FIG. I), as will be seen hereinafter, so as to maintain a perfectly horizontal position during the movement of the whole writing carriage on the frame 1.

The movable frame 16 is free to turn about the core 13, but comprises on the outside a fork 19 designed to engage the bar 9 of the stamping frame of the apparatus. This engagement limits the freedom of rotation of the frame 16. On said moveable frame 16 there is mounted the pin 20 on which there are keyed a gear 21 in mesh with the teeth 17a of the doubletoothed wheel 17, and the stamping wheel 22. The other set of teeth 17b of the wheel 17 is engaged by the two pawls 23 and 24, the first of which is attached to the fixed frame 15, while the second is attached to the movable frame 16. The toothing 17b of the double-toothed wheel 17 comprises 48 teeth and the stamping wheel 22 is provided with 12 stamping points, while the ratio between the teeth of the two toothings 17a and 21 is 2:1.

The lever system 4, 5, 6 is operated by the lever 5 pivoted at one end about halfway along the lever 4 and keyed at the opposite end on a shaft 25. The shaft 25 is the output shaft of the reduction gear which actuates the writing system. The lever 4 carries at one end a bush 26 slidable on the guide or pin 6. The pin 6 is at right angles to the slide bar 3 of the writing carriage 2. At the other end of the lever 4 there is located a bush in which the pin 18 of the writing carriage turns. The dimensioning of the lever 5, the distance between the fulcrum points of the lever 4 and the position of the shaft 25 are chosen in such manner that it is possible to cause the axis of the bush for the pin 18 to travel along a path exactly parallel to the bar 3 (except for errors below one-tenth of a millimetre).

The pad wheel or inking wheel 7 is mounted rotatably on the spindle 27, to which there is keyed a gear 28, and carries six inking pads 8 charged with inks of six different colors. The pads 8 are cylindrical bodies mounted loosely on their spindles 8. The gear 28 controls the movement of the wheel 7 and, to this end, is in mesh with a gear 29 mounted at end, end of the shaft 30 of the stamping mechanism and driven by the sprocket 31 of a small auxiliary motor 32.

The stamping frame of the apparatus according to the invention comprises a bar 9 parallel to the bar 3 on which the carriage slides and two levers 10 and II outside the frame I and fixed to the ends of the bar 9,- the levers being pivoted on the bar 3 and one of them carrying a roller 1 l on its free end.

The stamping frame is made to oscillate by the stamping and changeover mechanism 12 comprising in turn a cam 33 (with a nose 33' and recesses 33" and 33") located on the outer side of the frame 1 opposite that on which the pad wheel 7 is mounted and keyed on the shaft 30 of said mechanism, a cam 34 inside the frame and parallel to the cam 33 and keyed like the latter on the shaft 30, and a rocking lever 35 carrying a contact 36. The cam 33 is adapted to engage the roller ll of the lever 11, while the cam 34 is adapted to engage a roller 35 on the rocking lever 35 and the contact 36 of the latter is adapted to engage a fixed contact 37 to close the circuit of the motor driving the shaft 25. A spring 38 serves to hold the roller 11 of the lever 111 in contact with the cam 33 and similar spring means (not shown) provide similarly for a constant bearing action of the roller 35' of the lever 35 on the cam The changeover means for the variable to be measured are not shown in detail in the accompanying drawings. They are controlled by the shaft 30 and are indicated by a diagrammatic block 39 in FIG. 1. To describe the operation of the system according to the invention, it is appropriate to examine first of all the operation of the writing carriage 2 which, as already explained, is assumed to be mounted on the bar 3 by means of the cylindrical core 13 and with the pin 18 in the bush of the lever 4 and the fork l9 engaged over the bar 9. If the latter, oscillating as will be seen hereinafter, imparts a rotary movement in the direction of the arrow A (FIG. 4) to the movable frame 16 of the carriage, the double-toothed wheel 17 is compelled to move together with the movable frame 16 itself by the action of the pawl 24. Consequently, the stamping wheel 22 is lowered towards the chart sheet F (FIG. 4), but does not rotate about its own axis.

If, on the other hand, the frame 16 is rotated in the direction of the arrow 8 (FIG. 4), the toothed wheel 17 is held stationary in its position by the pawl 23.

Consequently, the stamping wheel 22 rotates about its own axis owing to the effect of the gear 21, which rolls on the toothed rim 17a. When the movable frame 16 returns to the original position, since movements in the direction of the arrow A do not cause the stamping wheel 22 to rotate about its own axis, everything returns to the starting position, except that the stamping wheel is shifted through a certain angle with respect to the original position. In view of the ratio between the number of teeth of the toothed wheels 17a and 21 and of the number of stamping points of the wheel 22, if the rotation in the direction of the arrow B impressed on the movable frame 16 is between one forty-eighth and one twenty-fourth of the angle of rotation, at the end of the operation the stamping wheel 22 will have been shifted by exactly one-twelfth of a revolution with respect to its original position. This position is therefore occupied by the stamping point immediately adjacent that which was therein in the preceding cycle, as will now be seen better. In the operation of the apparatus, the rotations of the movable frame 16 in the direction of the arrow A are utilized to imprint the dots on the chart F, while the rotations in the direction of the arrow B are utilized to replace or change the stamping point after each stamping operation.

The apparatus operates in the following manner: Let it be assumed that the measuring system of the instrument is connected to the first variable to be measured and that the cam 33 is in the position illustrated in FIG. 3a. Since the apparatus is in motion, after a brief period of time the recess 33" of the cam 33 will be presented below the roller 11' of the lever 11 and will cause a forward rotation of the stamping frame in the direction of the arrow A (FIG. 3). Under these conditions, pushed by the bar 9, the movable frame 16 of the carriage 2 rocks and the stamping wheel 22 is lowered on to the chart drum, imprinting a dot which identifies the measurements. As the shaft 30 which causes the cams 33 and 34 to rotate continues its rotation, the last-mentioned cam depresses the roller 35 of the lever 35 and the contact 36, 37 closes. The contact 36, 37 introduces into the measuring circuit-a sham or artificial voltage which causes the motor of the shaft 25 to rotate in such manner as to make the writing carriage 2 shift to the right-hand end of its travel. During this movement, as in all its other movements, the carriage 2 is shifted horizontally on the bar 3 without the fixed frame 15 of the movable carriage performing any rotation about the bar 3. After a certain length of time sufficient for the carriage to have in fact carried out the maneuver described, the roller 11 comes into contact with the nose 33' of the cam 33. In this way, a rotation in the direction of the arrow B (FIG. 3) is imparted to the lever 11 and, because of what has been said hereinbefore, this leads to a rotation of the stamping wheel 22, which will now present in the stamping position the stamping point following that which has been used in the preceding phase to imprint on the chart the dot identifying the measurement inserted.

Immediately afterwards, the roller 11" of the lever ll encounters the recess 33" of the cam 33 and, consequently, the stamping frame performs a rotation in the direction of the arrow A. Under these conditions, the stamping wheel does not shift any more, but the movable frame 16 of the carriage is lowered and, since the carriage itself is located at the end of the frame I in correspondence with the wheel 7, the stamping wheel 22 encounters the inking pads mounted on the wheel 7 and picks up a small amount of ink of a given color. After this, the stamping frame returns to the normal position and so also does the writing carriage.

At this point, the cam 34 controls the lever 35 so as to reopen the contact 36, 37, thereby eliminating the artificial voltage which has been compelling the writing carriage 2 to remain at the end of its travel to the right. At the same time, the measurement changeover device 39 actuated by the shaft 30 will have been brought into the following position and will connect variable No. 2 in the measuring circuit.

Under these conditions, the writing carriage 2 is brought to adopt a position corresponding to the value of variable No. 2. After a certain time, the recess 33"" of the cam 33 is presented at the roller of the lever 11, as a result of which the stamping of the second measurement dot is obtained. The cycle is repeated in the manner already described until all six dots corresponding to the six measurements connected to the instrument are stamped. After this, the dot corresponding to variable No. l is stamped again and so on.

The inking wheel 7 carries six pads in six different colors and perform l [/6 revolutions at each complete revolution of the shaft 30 and, therefore, of the cam 33. In these circumstances, each time the writing carriage 2 is brought to the right-hand end of its travel for inking, there is a different ink pad below it. Each stamping or printing point of the wheel 22 therefore comes to pick up ink of a different color and this serves to distinguish the six values measured. As has been said, the inked pads 8 are free to rotate about their own axes. Therefore, each time that a point of the stamping wheel 22 comes into contact with the respective pad, since the inking wheel 7 continues to rotate, the pad itself undergoes a small rotation about its own axis. This is very important, because it avoids stamping or printing points always coming into contact with the same zone of the pads, which would cause rapid consumption of ink and rapid wear of the pads themselves.

It will be perfectly clear to experts acquainted with the techniques normally employed for constructing conventional apparatus of the kind to which the present invention belongs how many advantages the latter affords in comparison with the first mentioned. Up to now, in fact, in conventional apparatus, control of the carriage has been provided for by a wire system, which ensures many less requirements as far as the accuracy, reliability and working life of the mechanical system used in the apparatus according to the invention are concerned.

Moreover, the inking system for the writing points is carried by the writing carriage, which thus has greater inertia and a more complex and sensitive structure. In the apparatus according to the invention, on the other hand, these two parts have been made completely separate and independent by making only the carriage movable and associating the inking writing operation and in the opposite direction the replacement or changing of the stamping point, the carriage being moreover actuated by means other than the bar along which the carriage itself slides, which can therefore be kept round and plain, instead of profiled (for control of the transverse movements of the carriage), as has been the case in the conventional technique.

lclaim:

1. Writing apparatus for recording the values of a plurality of variables in a plurality of colors on a continuously moving chart comprising a holding and supporting frame, a writing carriage mounted for movement on said frame to stamping positions indicative of the value of said variables and to an inking position before each of said stamping position movements for selecting a color representing a said variable, the stamping and inking operations being effected by oscillation of said writing carriage at right angles to said movement, said carriage comprising a fixed frame, a movable frame mounted for movement with respect to said fixed frame, stamping means on said movable frame, means for moving said writing carriage to said stamping and inking positions responsive to the value of said variables, means for inking said stamping means including a wheel mounted rotatably on said frame separate from said writing carriage and supporting a plurality of inking pads of different colors, means for controlling said writing carriage and said means for inking so that said stamping means will be inked with a color before it is used to record a variable, said controlling means including a first shaft mounted on said frame, drive means for rotating said first shaft, first cam means on said first shaft having a first portion for controlling the stamping operation and a second portion for controlling the inking operation, means actuated by said first cam means for providing said oscillation of said writing carriage, a second shaft for moving said wheel to select a color thereof, means interconnecting said first and second shafts for conjoint rotation, second cam means on said first shaft, and means actuated by said second cam means for connecting an artificial voltage to said means for moving said carriage to said inking position between stamping operations.

2. Apparatus as claimed in claim' 1, wherein said means for moving said carriage includes a mechanical lever system connecting said moving means to said fixed frame.

3. Apparatus as claimed in claim 1, wherein said stamping means is a wheel with stamping points and means rotating the wheel between one inking and stamping operation and another. v

4. Apparatus as claimed in claim 3, said means for rotating the last-named wheel including a double-toothed wheelwith two pawls mounted so that the oscillation of the writing carriage in one direction causes the rotation of the doubletoothed wheel, and means for preventing oscillations of the carriage in the opposite direction.

5. Apparatus as claimed in claim 4, wherein said plurality of inking pads are in the form of cylindrical bearings mounted loosely on pins projecting from the periphery of said wheel at 

1. Writing apparatus for recording the values of a plurality of variables in a plurality of colors on a continuously moving chart comprising a holding and supporting frame, a writing carriage mounted for movement on said frame to stamping positions indicative of the value of said variables and to an inking position before each of said stamping position movements for selecting a color representing a said variable, the stamping and inking operations being effected by oscillation of said writing carriage at right angles to said movement, said carriage comprising a fixed frame, a movable frame mounted for movement with respect to said fixed frame, stamping means on said movable frame, means for moving said writing carriage to said stamping and inking positions responsive to the value of said variables, means for inking said stamping means including a wheel mounted rotatably on said frame separate from said writing carriage and supporting a plurality of inking pads of different colors, means for controlling said writing carriage and said means for inking so that sAid stamping means will be inked with a color before it is used to record a variable, said controlling means including a first shaft mounted on said frame, drive means for rotating said first shaft, first cam means on said first shaft having a first portion for controlling the stamping operation and a second portion for controlling the inking operation, means actuated by said first cam means for providing said oscillation of said writing carriage, a second shaft for moving said wheel to select a color thereof, means interconnecting said first and second shafts for conjoint rotation, second cam means on said first shaft, and means actuated by said second cam means for connecting an artificial voltage to said means for moving said carriage to said inking position between stamping operations.
 2. Apparatus as claimed in claim 1, wherein said means for moving said carriage includes a mechanical lever system connecting said moving means to said fixed frame.
 3. Apparatus as claimed in claim 1, wherein said stamping means is a wheel with stamping points and means rotating the wheel between one inking and stamping operation and another.
 4. Apparatus as claimed in claim 3, said means for rotating the last-named wheel including a double-toothed wheel with two pawls mounted so that the oscillation of the writing carriage in one direction causes the rotation of the double-toothed wheel, and means for preventing oscillations of the carriage in the opposite direction.
 5. Apparatus as claimed in claim 4, wherein said plurality of inking pads are in the form of cylindrical bearings mounted loosely on pins projecting from the periphery of said wheel at right angles to said wheel.
 6. Apparatus as claimed in claim 5, the number of stamping points of the wheel of the writing carriage and the number of inking pads of the wheel of the inking means and the means for rotating the two last-named wheels being such as to cause each stamping point to effect its inking always on the same pad but on different zones thereof. 